From d5c54ff3d1db0a4348fa04d8e78f3bf6063e3afc Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Mon, 7 Dec 2015 17:21:27 +0100
Subject: [PATCH 45/53] i2c: add mt7621 driver

Signed-off-by: John Crispin <blogic@openwrt.org>
---
 drivers/i2c/busses/Kconfig      |    4 +
 drivers/i2c/busses/Makefile     |    1 +
 drivers/i2c/busses/i2c-mt7621.c |  303 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 308 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-mt7621.c

--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -868,6 +868,11 @@ config I2C_RALINK
 	depends on RALINK && !SOC_MT7621
 	select OF_I2C
 
+config I2C_MT7621
+	tristate "MT7621/MT7628 I2C Controller"
+	depends on RALINK && (SOC_MT7620 || SOC_MT7621)
+	select OF_I2C
+
 config HAVE_S3C2410_I2C
 	bool
 	help
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -85,6 +85,7 @@ obj-$(CONFIG_I2C_PUV3)		+= i2c-puv3.o
 obj-$(CONFIG_I2C_PXA)		+= i2c-pxa.o
 obj-$(CONFIG_I2C_PXA_PCI)	+= i2c-pxa-pci.o
 obj-$(CONFIG_I2C_RALINK)	+= i2c-ralink.o
+obj-$(CONFIG_I2C_MT7621)	+= i2c-mt7621.o
 obj-$(CONFIG_I2C_QUP)		+= i2c-qup.o
 obj-$(CONFIG_I2C_RIIC)		+= i2c-riic.o
 obj-$(CONFIG_I2C_RK3X)		+= i2c-rk3x.o
--- /dev/null
+++ b/drivers/i2c/busses/i2c-mt7621.c
@@ -0,0 +1,433 @@
+/*
+ * drivers/i2c/busses/i2c-mt7621.c
+ *
+ * Copyright (C) 2013 Steven Liu <steven_liu@mediatek.com>
+ * Copyright (C) 2016 Michael Lee <igvtee@gmail.com>
+ *
+ * Improve driver for i2cdetect from i2c-tools to detect i2c devices on the bus.
+ * (C) 2014 Sittisak <sittisaks@hotmail.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/reset.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/of_platform.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+
+#define REG_SM0CFG0		0x08
+#define REG_SM0DOUT		0x10
+#define REG_SM0DIN		0x14
+#define REG_SM0ST		0x18
+#define REG_SM0AUTO		0x1C
+#define REG_SM0CFG1		0x20
+#define REG_SM0CFG2		0x28
+#define REG_SM0CTL0		0x40
+#define REG_SM0CTL1		0x44
+#define REG_SM0D0		0x50
+#define REG_SM0D1		0x54
+#define REG_PINTEN		0x5C
+#define REG_PINTST		0x60
+#define REG_PINTCL		0x64
+
+/* REG_SM0CFG0 */
+#define I2C_DEVADDR_MASK	0x7f
+
+/* REG_SM0ST */
+#define I2C_DATARDY		BIT(2)
+#define I2C_SDOEMPTY		BIT(1)
+#define I2C_BUSY		BIT(0)
+
+/* REG_SM0AUTO */
+#define READ_CMD		BIT(0)
+
+/* REG_SM0CFG1 */
+#define BYTECNT_MAX		64
+#define SET_BYTECNT(x)		(x - 1)
+
+/* REG_SM0CFG2 */
+#define AUTOMODE_EN		BIT(0)
+
+/* REG_SM0CTL0 */
+#define ODRAIN_HIGH_SM0		BIT(31)
+#define VSYNC_SHIFT		28
+#define VSYNC_MASK		0x3
+#define VSYNC_PULSE		(0x1 << VSYNC_SHIFT)
+#define VSYNC_RISING		(0x2 << VSYNC_SHIFT)
+#define CLK_DIV_SHIFT		16
+#define CLK_DIV_MASK		0xfff
+#define DEG_CNT_SHIFT		8
+#define DEG_CNT_MASK		0xff
+#define WAIT_HIGH		BIT(6)
+#define DEG_EN			BIT(5)
+#define CS_STATUA		BIT(4)
+#define SCL_STATUS		BIT(3)
+#define SDA_STATUS		BIT(2)
+#define SM0_EN			BIT(1)
+#define SCL_STRECH		BIT(0)
+
+/* REG_SM0CTL1 */
+#define ACK_SHIFT		16
+#define ACK_MASK		0xff
+#define PGLEN_SHIFT		8
+#define PGLEN_MASK		0x7
+#define SM0_MODE_SHIFT		4
+#define SM0_MODE_MASK		0x7
+#define SM0_MODE_START		0x1
+#define SM0_MODE_WRITE		0x2
+#define SM0_MODE_STOP		0x3
+#define SM0_MODE_READ_NACK	0x4
+#define SM0_MODE_READ_ACK	0x5
+#define SM0_TRI_BUSY		BIT(0)
+
+/* timeout waiting for I2C devices to respond (clock streching) */
+#define TIMEOUT_MS              1000
+#define DELAY_INTERVAL_US       100
+
+struct mtk_i2c {
+	void __iomem *base;
+	struct clk *clk;
+	struct device *dev;
+	struct i2c_adapter adap;
+	u32 cur_clk;
+	u32 clk_div;
+	u32 flags;
+};
+
+static void mtk_i2c_w32(struct mtk_i2c *i2c, u32 val, unsigned reg)
+{
+	iowrite32(val, i2c->base + reg);
+}
+
+static u32 mtk_i2c_r32(struct mtk_i2c *i2c, unsigned reg)
+{
+	return ioread32(i2c->base + reg);
+}
+
+static int poll_down_timeout(void __iomem *addr, u32 mask)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(TIMEOUT_MS);
+
+	do {
+		if (!(readl_relaxed(addr) & mask))
+			return 0;
+
+		usleep_range(DELAY_INTERVAL_US, DELAY_INTERVAL_US + 50);
+	} while (time_before(jiffies, timeout));
+
+	return (readl_relaxed(addr) & mask) ? -EAGAIN : 0;
+}
+
+static int mtk_i2c_wait_idle(struct mtk_i2c *i2c)
+{
+	int ret;
+
+	ret = poll_down_timeout(i2c->base + REG_SM0ST, I2C_BUSY);
+	if (ret < 0)
+		dev_dbg(i2c->dev, "idle err(%d)\n", ret);
+
+	return ret;
+}
+
+static int poll_up_timeout(void __iomem *addr, u32 mask)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(TIMEOUT_MS);
+	u32 status;
+
+	do {
+		status = readl_relaxed(addr);
+		if (status & mask)
+			return 0;
+		usleep_range(DELAY_INTERVAL_US, DELAY_INTERVAL_US + 50);
+	} while (time_before(jiffies, timeout));
+
+	return -ETIMEDOUT;
+}
+
+static int mtk_i2c_wait_rx_done(struct mtk_i2c *i2c)
+{
+	int ret;
+
+	ret = poll_up_timeout(i2c->base + REG_SM0ST, I2C_DATARDY);
+	if (ret < 0)
+		dev_dbg(i2c->dev, "rx err(%d)\n", ret);
+
+	return ret;
+}
+
+static int mtk_i2c_wait_tx_done(struct mtk_i2c *i2c)
+{
+	int ret;
+
+	ret = poll_up_timeout(i2c->base + REG_SM0ST, I2C_SDOEMPTY);
+	if (ret < 0)
+		dev_dbg(i2c->dev, "tx err(%d)\n", ret);
+
+	return ret;
+}
+
+static void mtk_i2c_reset(struct mtk_i2c *i2c)
+{
+	u32 reg;
+	device_reset(i2c->adap.dev.parent);
+	barrier();
+
+	/* ctrl0 */
+	reg = ODRAIN_HIGH_SM0 | VSYNC_PULSE | (i2c->clk_div << CLK_DIV_SHIFT) |
+		WAIT_HIGH | SM0_EN;
+	mtk_i2c_w32(i2c, reg, REG_SM0CTL0);
+
+	/* auto mode */
+	mtk_i2c_w32(i2c, AUTOMODE_EN, REG_SM0CFG2);
+}
+
+static void mtk_i2c_dump_reg(struct mtk_i2c *i2c)
+{
+	dev_dbg(i2c->dev, "cfg0 %08x, dout %08x, din %08x, " \
+			"status %08x, auto %08x, cfg1 %08x, " \
+			"cfg2 %08x, ctl0 %08x, ctl1 %08x\n",
+			mtk_i2c_r32(i2c, REG_SM0CFG0),
+			mtk_i2c_r32(i2c, REG_SM0DOUT),
+			mtk_i2c_r32(i2c, REG_SM0DIN),
+			mtk_i2c_r32(i2c, REG_SM0ST),
+			mtk_i2c_r32(i2c, REG_SM0AUTO),
+			mtk_i2c_r32(i2c, REG_SM0CFG1),
+			mtk_i2c_r32(i2c, REG_SM0CFG2),
+			mtk_i2c_r32(i2c, REG_SM0CTL0),
+			mtk_i2c_r32(i2c, REG_SM0CTL1));
+}
+
+static int mtk_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+		int num)
+{
+	struct mtk_i2c *i2c;
+	struct i2c_msg *pmsg;
+	int i, j, ret;
+	u32 cmd;
+
+	i2c = i2c_get_adapdata(adap);
+
+	for (i = 0; i < num; i++) {
+		pmsg = &msgs[i];
+		cmd = 0;
+
+		dev_dbg(i2c->dev, "addr: 0x%x, len: %d, flags: 0x%x\n",
+				pmsg->addr, pmsg->len, pmsg->flags);
+
+		/* wait hardware idle */
+		if ((ret = mtk_i2c_wait_idle(i2c)))
+			goto err_timeout;
+
+		if (pmsg->flags & I2C_M_TEN) {
+			dev_dbg(i2c->dev, "10 bits addr not supported\n");
+			return -EINVAL;
+		} else {
+			/* 7 bits address */
+			mtk_i2c_w32(i2c, pmsg->addr & I2C_DEVADDR_MASK,
+					REG_SM0CFG0);
+		}
+
+		/* buffer length */
+		if (pmsg->len == 0) {
+			dev_dbg(i2c->dev, "length is 0\n");
+			return -EINVAL;
+		} else
+			mtk_i2c_w32(i2c, SET_BYTECNT(pmsg->len),
+					REG_SM0CFG1);
+
+		j = 0;
+		if (pmsg->flags & I2C_M_RD) {
+			cmd |= READ_CMD;
+			/* start transfer */
+			barrier();
+			mtk_i2c_w32(i2c, cmd, REG_SM0AUTO);
+			do {
+				/* wait */
+				if ((ret = mtk_i2c_wait_rx_done(i2c)))
+					goto err_timeout;
+				/* read data */
+				if (pmsg->len)
+					pmsg->buf[j] = mtk_i2c_r32(i2c,
+							REG_SM0DIN);
+				j++;
+			} while (j < pmsg->len);
+		} else {
+			do {
+				/* write data */
+				if (pmsg->len)
+					mtk_i2c_w32(i2c, pmsg->buf[j],
+							REG_SM0DOUT);
+				/* start transfer */
+				if (j == 0) {
+					barrier();
+					mtk_i2c_w32(i2c, cmd, REG_SM0AUTO);
+				}
+				/* wait */
+				if ((ret = mtk_i2c_wait_tx_done(i2c)))
+					goto err_timeout;
+				j++;
+			} while (j < pmsg->len);
+		}
+	}
+	/* the return value is number of executed messages */
+	ret = i;
+
+	return ret;
+
+err_timeout:
+	mtk_i2c_dump_reg(i2c);
+	mtk_i2c_reset(i2c);
+	return ret;
+}
+
+static u32 mtk_i2c_func(struct i2c_adapter *a)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm mtk_i2c_algo = {
+	.master_xfer	= mtk_i2c_master_xfer,
+	.functionality	= mtk_i2c_func,
+};
+
+static const struct of_device_id i2c_mtk_dt_ids[] = {
+	{ .compatible = "mediatek,mt7621-i2c" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, i2c_mtk_dt_ids);
+
+static struct i2c_adapter_quirks mtk_i2c_quirks = {
+        .max_write_len = BYTECNT_MAX,
+        .max_read_len = BYTECNT_MAX,
+};
+
+static void mtk_i2c_init(struct mtk_i2c *i2c)
+{
+	i2c->clk_div = clk_get_rate(i2c->clk) / i2c->cur_clk;
+	if (i2c->clk_div > CLK_DIV_MASK)
+		i2c->clk_div = CLK_DIV_MASK;
+
+	mtk_i2c_reset(i2c);
+}
+
+static int mtk_i2c_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct mtk_i2c *i2c;
+	struct i2c_adapter *adap;
+	const struct of_device_id *match;
+	int ret;
+
+	match = of_match_device(i2c_mtk_dt_ids, &pdev->dev);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "no memory resource found\n");
+		return -ENODEV;
+	}
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(struct mtk_i2c), GFP_KERNEL);
+	if (!i2c) {
+		dev_err(&pdev->dev, "failed to allocate i2c_adapter\n");
+		return -ENOMEM;
+	}
+
+	i2c->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(i2c->base))
+		return PTR_ERR(i2c->base);
+
+	i2c->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(i2c->clk)) {
+		dev_err(&pdev->dev, "no clock defined\n");
+		return -ENODEV;
+	}
+	clk_prepare_enable(i2c->clk);
+	i2c->dev = &pdev->dev;
+
+	if (of_property_read_u32(pdev->dev.of_node,
+				"clock-frequency", &i2c->cur_clk))
+		i2c->cur_clk = 100000;
+
+	adap = &i2c->adap;
+	adap->owner = THIS_MODULE;
+	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
+	adap->algo = &mtk_i2c_algo;
+	adap->retries = 3;
+	adap->dev.parent = &pdev->dev;
+	i2c_set_adapdata(adap, i2c);
+	adap->dev.of_node = pdev->dev.of_node;
+	strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));
+	adap->quirks = &mtk_i2c_quirks;
+
+	platform_set_drvdata(pdev, i2c);
+
+	mtk_i2c_init(i2c);
+
+	ret = i2c_add_adapter(adap);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add adapter\n");
+		clk_disable_unprepare(i2c->clk);
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "clock %uKHz, re-start not support\n",
+			i2c->cur_clk/1000);
+
+	return ret;
+}
+
+static int mtk_i2c_remove(struct platform_device *pdev)
+{
+	struct mtk_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adap);
+	clk_disable_unprepare(i2c->clk);
+
+	return 0;
+}
+
+static struct platform_driver mtk_i2c_driver = {
+	.probe		= mtk_i2c_probe,
+	.remove		= mtk_i2c_remove,
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "i2c-mt7621",
+		.of_match_table = i2c_mtk_dt_ids,
+	},
+};
+
+static int __init i2c_mtk_init (void)
+{
+	return platform_driver_register(&mtk_i2c_driver);
+}
+subsys_initcall(i2c_mtk_init);
+
+static void __exit i2c_mtk_exit (void)
+{
+	platform_driver_unregister(&mtk_i2c_driver);
+}
+module_exit(i2c_mtk_exit);
+
+MODULE_AUTHOR("Steven Liu <steven_liu@mediatek.com>");
+MODULE_DESCRIPTION("MT7621 I2c host driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:MT7621-I2C");
